Polyurethanes prepared from oxyalkylated cyanoguanidine



United States Patent 3,288,733 POLYURETHANES PREPARED FROM OXY-ALKYLATED CYANOGUANIDINE Donald W. Kaiser, Hamtlen, Conn., assignor toOlin Mathieson Chemical Corporation, a corporation of Virgnna N0Drawing. Original application May 1, 1963, Ser. No. 277,123, now PatentNo. 3,262,941. Divided and this application Oct. 18, 1965, Ser. No.510,425

4 Claims. (Cl. 2602.5)

The present invention relates to a novel process for oxyalkylatingcyanoguanidine.

The present application is a division of co-pending application, SerialNo. 277,123, filed May 1, 1963, now US. Patent 3,262,941 by Donald W.Kaiser.

Cyanoguanidine has previously been oxyethylated, for example asdescribed in US. Patents 2,349,557 and 2,375,- 012 by heating it underpressure with ethylene oxide and water but with no catalyst. Severalhours at temperatures to 125 C. were required to combine 2 molecules ofethylene oxide with one of cyanoguanidine.

It has been found, surprisingly and unexpectedly, that cyanoguanidinereacts readily with propylene oxide in the presence of a solventcontaining dimethyl sulfoxide in an amount of from 5 to 100 percent byweight of the total solvent portion. The reaction is conducted atatmospheric pressure in the presence of a basic catalyst, at atemperature of between about 75 and 175 C. and the ratio ofcyanoguanidine to alkylene oxide is from 1:5 to 1:125. The reactants aremixed in the desired proportions at the desired temperature and in thepresence of a basic catalyst.

In the present specification and claims the term alkylene oxide isintended to include alkylene oxides having 3 to 8 carbon atoms,including alkylene oxides containing noninterferring substituents andaralkylene oxides, for example, styrene oxide. The unsubstitutedalkylene oxides, especially the lower alkylene oxides are preferred, forexample, propylene oxide, butylene oxide, isobutylene oxide and n-hexyloxide. The cycloalkylene oxides may also be used, for example,cyclobutylene oxide and cyclohexylene oxide.

The reaction is accelerated by employing elevated temperatures from 75to 175 C. and preferably from 90 to 140 C. and by the use of a basiccatalyst, either organic or inorganic. The catalyst is preferably analkali metal hydroxide or alkoxide, for example, sodium hydroxide,potassium hydroxide or sodium methoxide. The reaction is initiallyexothermic and conventional cooling means are normally employed tomaintain the reaction at the desired temperature. The reaction time isnot critical and will vary depending upon the degree of completiondesired, temperature, reactants and proportions.

The molar ratio of the cyanoguanidine to alkylene oxide may vary from1:5 to 1:125 Thus oxyalkylated products can be tailormade for particularproperties depending upon the proportion of alkylene oxide employed. Theproperties of the resultant product depends on the character of thesubstituents and the proportion of alkylene oxide employed.

The reaction is conducted in a solvent containing dimethyl sulfoxide inan amount of from 5 to 100 percent by weight of the solvent portion. Itis a surprising feature of the present invention that when at least aportion of the solvent component is dimethyl sulfoxide, thecyanoguanidine is readily oxyalkylated. The total solvent component mayconsist of the dimethyl sulfoxide, or for economy, varying amounts ofless expensive and convenient solvents may be employed, such as toluene,xylene, dioxane, etc.

The minimum proportion of dimethyl sulfoxide used is suitably suflicientto dissolve at least a portion of the cyanoguanidine. As theoxyalkylation proceeds, the retion mixture by conventional methods, forexample, addition of acid to the mixture to neutralize the basiccatalyst plus the basicity of the resultant polyol, distillation ofexcess solvent and recovery of the product by filtration. The acid usedfor neutralization of the catalyst is suitably inorganic, for example,monoammonium phosphate, phosphoric, hydrochloric, sulfuric or sulfamicacid. It may also be organic, for example, acetic, trichloroacetic,oleic or linoleic acid. Tall oil is especially advantageous. Thecyanoguanidine can be partially oxyalkylated, solvent removed bydistillation, and oxyalkylation continued. The final pH is suitably 4 to12.

Cyanoguanidine is essentially a neutral compound, with dissociationconstants of:

However, the alkoxylated products are strongly basic. It is believedthat propylene oxide, for example, reacts in the following fashion tocreate a strong base, which is then further oxypropylated:

This invention is not limited, however, to the above interpretation.

With the creating of a strong base, excess acid over that required toneutralize the basic catalyst is required to lower the pH of theresultant polyol. Since mineral acids and tall oil are cheap, anunexpected advantage is ac.- crued and the cost of the polyol product isappreciably cheapened.

The apparent pH, as this term is used in the present specification,including the examples, is determined by measuring the pH of a solutionof 10 grams of the sample in 50 ml. of a mixture of 10 parts by volumeof isopropanol and 6 parts of water.

The utilization of dimethyl sulfoxide as solvent oifers severalsignificant and unexpected advantages in the preparation of oxyalkylatedcyanoguanidine. The use of a solvent comprising dimethyl sulfoxideallows the convenient use of lower reaction temperature and shortens thereaction time. In addition, no pressure is required.

The oxyalkylated products of the present invention have highly desirablecharacteristics as the polyol component in flexible, rigid andsemi-rigid polyurethane films and foams. The foam compositions areformed by reaction of a diisocyanate in the presence of a foaming agentand catalyst, with the oxyalkylation products of the present invention.The resultant polyurethane foams are characterized by greatly improvedflame retardance, due to the presence of nitrogen and a mineral acid.They also have excellent humid aging properties and hydrolyticstability. In addition, the oxyalkylated products of the presentinvention may be used as anticorrosion agents when H PO is the acid ofneutralization and as dispersants for lubricating oils, plasticizers orstabilizers for poly(vinyl chloride) resins, epoxy resin curing agents,and reactants for the preparation of polyester resins. The salts, suchas the phosphates, are water soluble and may be utilized as cationicdetergents and softening agents for cotton.

Suitable organic polyisocyanates which may be employed in thepreparation of the polyurethane foams include di-isocyanates,tri-isocyanates, and polyisocyanates. Especially preferred are mixedisomers of toluylene di-isocyanate which are readily availablecommercially. Other suitable isocyanates include methylene-bis-(4-phenyl isocyanate), 3,3-bitolylene-4,4'-di-isocyanate, 3,3'-dimethoxy-4,4-bi-phenylene di-isocyanate, naphthalene-1,4-diisocyanate, hexamethylene di-isocyanate, 'PAPI(polymethylenepolyphenyl isocyanate) and 1,4- phenylene di-isocyanate. The amount ofisocyanate employed in the preparation of the polyurethane foams shouldbe suflicient to provide at least 0.7 NCO groups based on. the number ofhydroxyl groups present in the alkoxylated cyanoguanidine of the presentinvention, the number of hydroxyl groups in any additive employed andthe number of hydroxyl groups employed in the foaming agent. An excessof isocyanate compound may be conveniently employed; however, this isgenerally undesirable due to the high cost of the isocyanate compounds.It is preferable, therefore, to employ no greater than 1.5 NCO groupsbased on the number of hydroxyl groups and preferably between about 0.9and 1.1 NCO groups.

Pre-polymers can be formed from the polyols of the present invention byreaction with a suitable excess of a di-isocyanate. The proportion ofdi-isocyanate in these prepolymers is suitable to provide from 1.4 to3.0 NCO groups per hydroxyl group. The prepolymers are subsequentlyreacted with additional polyol with or without additional di-isocyanatein applications where the use of pro-polymers is advantageous.

The polyurethane foams are prepared in the presence of a foaming agentand a reaction catalyst. The foaming agent employed may be any of thoseknown to be useful for this purpose, such as water, the halogenatedhydrocarbons and mixtures thereof. Typical halogenated hydrocarbonsinclude but are not limited to, the following:monofiuorotrichloromethane, difiuorodichloromethane, 1,1,2trichloro-1,2,2 trifluoroethane, methylene chloride, chloroform andcarbon tetrachloride. The amount of foaming agent employed may be variedwithin a wide range. Generally however, the halogenated hydrocarbons areemployed in an amount of from 1 to 50 parts by weight per 100 parts byweight of the ad-' duct of the present invention, and generally thewater, when employed, is in an amount of from 0.1 to parts by weight per100 parts by weight of the adduct of the present invention.

The polyurethane foams are prepared in the presence of a catalyticamount of a reaction catalyst. The catalyst employed may be any of thecatalysts known to be useful for this purpose, including tertiary aminesand metallic salts. Suitable tertiary amines include N-methylmorpholine, N-hydroxyethyl morpholine, triethylene diamine,triethylamine, trirnethylamine and N,N-dimethylethanolamine. Typicalmetallic salts include, for example, the salts of antimony, tin andiron, for example, dibutyltin dilaurate and stannous octoate. Thecatalyst is usually employed in an amount of from 0.1 to 2.0 percent byweight based on the coalkoxylation product of the present invention.

In the preparation of the polyurethane foams of the present inventionminor amounts of emulsifier are preferably used to improve the cellstructure of the polyurethane foam. Typical of such emulsifiers are thesilicone oils and soaps. Generally up to 2 parts by weight of thesurfactant is employed per 100 parts of polyol.

Various additives can be employed which serve to provide differentproperties, e.g. fillers, such as clay, calcium carbonate or calciumsulfate. These additives lower the cost and improve physical properties.Dyes may Example I A stirred mixture of 84 g. (1.0 mole) ofcyanoguanidine, 3.5 g. of 85 percent potassium hydroxide and 150 ml.(160 g.) of dimethyl sulfoxide was heated under nitrogen to C. andpropylene oxide was gradually added to the solution. Reaction wasinitially exothermic. A total of 421 g. (7.25 moles) of propylene oxidewas reacted.

After propoxylation, 5.24 g. of 50 percent sulfuric acid was added toneutralize the potassium hydroxide. An additional 190 g. of 50 percentsulfuric acid was then required to lower the pH. Attapulgus clay (30 g.)was added and the mixture was stripped at 100 to C. under water pumpvacuum for 4 hours. The hot mixture was filtered through Celite coveredpaper and stripping was continued at 1 to 2 mm. with a final temperatureof C. Analysis of the product gave the following values:

Hydroxyl number 368 Acid number 12.69

Percent water 0.12 Apparent pH 4.1 Viscosity 100 15., centistokes 104,706

Example II Propylene oxide was gradually added to a stirred solution of168 g. (2.0 moles) of cyanoguanidine and 8 g. of 85 percent potassiumhydroxide in 200 ml. (220 g.) of dimethyl sulfoxide heated to 100 C.under nitrogen. A total of 580 g. (10 moles) of propylene oxide wasreacted. When cool, the potassium hydroxide was neutralized with 7 g. of85 percent phosphoric acid. The high alkalinity of the polyol wasneutralized with 1208 g. of Unitol DT (tall oil). Attapulgus clay (75g.) was added and the mixture stripped 2 hours at 126 C. under waterpump vacuum. The mixture was filtered through a Celite covered filterpaper. The filtrate was stripped further at 150 C. and at 1 to 2 mm.Analysis gave the following values:

Hydroxyl number 168 Alkaline number 2.86 Percent, water 0.03 Apparent pH11.5 Viscosity 100 F., centistokes 775 Example III A stirred mixture of168 g. (2.0 moles) of cyanoguanidine and 8 g. of 85 percent potassiumhydroxide in 200 ml. (220 g.) of dimethyl sulfoxide was heated to 70 C.under an atmosphere of nitrogen. Propoxylation was carried out at 70 C.,introducing 380 g. of propylene oxide. The temperature was increased to85 C. and propoxylation was completed. A total of 580 g. 10 moles) ofpropylene oxide reacted. The catalyst was neutralized with 7 g. of 85percent phosphoric acid. The addition of 604 g. of tall oil (Unitol DT)was followed by treatment with 75 g. of Attaclay at 75 C. under 30 to 30mm. pressure for 1 hour. The mixture was filtered through Celite andstripped at 150 C. at a pressure below 1 mm. Analyses gave the followingvalues:

Hydroxyl number 270 Alkaline number 5.52 Water, percent 0.04 Apparent pH12.1 Viscosity at 100 F., centistokes 918 G A polyurethane foam wasprepared using the following formulation:

Component: Parts by weight Polyol of Example III 100 Emulsifier(silicone) 1.3 Catalyst (l,2,4-trimethyl-piperazine) 0.2 Foaming agent(Freon 11)* 20 Tolylene di-isocyanate 45 Freon 11 is a trademark of E.I. du Pont de Nemours and Company, Inc., for its brand of'trichloromonofiuoromethane.

What is claimed is:

1. The process of preparing a polyurethane which comprises admixing (A)an organic polyisocyanate, (B) 0.1 to 2 parts of a reaction catalyst per100 parts of (C) a liquid reaction product formed by admixing (1) abasic catalyst, (2) cyanoguanidine and (3) dimethyl sulfoxide to form aliquid reaction mixture, the weight ratio of (2) to (3) being between1:1 and 1:5, heating said liquid reaction. mixture to a temperaturebetween 75 and 175 C. while passing into said liquid reaction mixture analkylene oxide having 3 to 8 carbon atoms, the weight ratio of (2) tosaid alkylene oxide being between 1:5 and 1:125 and then removing saiddimethyl sulfoxide, the proportion of (A) providing 0.7 to 1.5

CNO groups for each hydroxyl group contained in (C).

2. The process of preparing a polyurethane foam which comprises admixing(A) an organic polyisocyanate, (B) 1 to parts of a foaming agent, (C)0.1 to 2 parts of reaction catalyst per parts of (D) a liquid reactionproduct formed by admixing (l) a basic catalyst, (2) cyanoguanidine and(3) dimethyl sulfoxide to form a liquid reaction mixture, the weightratio of (2) to (3) being between 1:1 and 1:5, heating said liquidreaction mixture to a temperature between 75 and C. While passing intosaid liquid reaction mixture an alkylene oxide having 3 to 8 carbonatoms, the weight ratio of (2) to said alkylene oxide being between 1:5and 1:125 and then removing said dimethyl sulfoxide, the proportion of(A) providing from 0.7 to 1.5 CNO groups for each hydroxyl groupcontained in (D).

3. The polyurethane produced by the process of claim 1.

4. The polyurethane foam produced by the process of claim 2.

No references cited.

LEON I. BERCOVITZ, Primary Examiner.

DONALD E. CZAJA, Examiner.

2. THE PROCESS OF PREPARING A POLYURETHANE FOAM WHICH COMPRISES ADMIXING(A) AN ORGANIC POLYISOCYANATE, (B) 1 TO 50 PARTS OF A FOAMING AGENT, (C)0.1 TO 2 PARTS OF REACTION CATALYST PER 100 PARTS OF (D) A LIQUIDREACTION PRODUCT FORMED BY ADMIXING (1) A BASIC CATALYST, (2)CYANOGUANIDINE AND (3) DIMETHYL SULFOXIDE TO FORM A LIQUID REACTIONMIXTURE, THE WEIGHT RATIO OF (2) TO (3) BEING BETWEEN 1:1 AND 1:5,HEATING SAID LIQUID REACTION MIXTURE TO A TEMPERATURE BETWEEN 75* AND175*C. WHILE PASSING INTO SAID LIQUID REACTION MIXTURE AN ALKYLENE OXIDEHAVING 3 TO 8 CARBON ATOMS, THE WEIGHT RATIO OF (2) TO SAID ALKYLENEOXIDE BEING BETWEEN 1:5 AND 1:125 AND THEN REMOVING SAID DIMETHYLSULFOXIDE, THE PROPORTION OF (A) PROVIDING FROM 0.7 TO 1.5 CNO GROUPSFOR EACH HYDROXYL GROUP CONTAINED IN (D).